docs: a real navigation, a landing page, and answers newcomers actually need The wiki had good pages and no way to move between them. This adds a sidebar and a footer, rewrites the home page as a product landing, corrects the setup flow to its five real steps, and adds FAQ and Troubleshooting pages. It also fixes repository links that pointed at a branch the repository does not use, and records the two version numbers the product carries on purpose.
docs: seed the wiki with everything the repository knows Thirteen pages in English, synthesized from docs/, the 34 odd/tasks records and the verified session memory: what PiCode is, getting it, the first-run wizard, architecture, the source build, the patch system, Pi inside, Gentle AI and ODD, distribution and licensing, CI and releases, the ADR index, roadmap and known state, and a glossary. Mirror of the repository's wiki/ folder.